Erosional Landforms
Erosional landforms are physical features on the Earth's surface that have been shaped by the processes of erosion, such as the wearing away of rock and soil by water, wind, or ice. Examples of erosional landforms include valleys, canyons, cliffs, and sea stacks. These landforms are the result of the gradual removal of material from the Earth's surface over time.
6 Key excerpts on "Erosional Landforms"
eBook - ePub- Simon Bell(Author)
- 2012(Publication Date)
- Routledge(Publisher)
...Soft rocks may be eroded quickly by water as in the badlands of the USA or along river valleys. Examples of unique geological formations that have exerted a major influence on the geomorphology. Igneous intrusions, volcanic plugs and lava flows can determine the structure and the character of a landscape. The city of Edinburgh in Scotland is a prime example of this (see Chapter Eight). Examples of geological formations, often deep down in the earth, such as oil, coal or minerals of economic value which have led to certain settlement or industrial patterns as well as large-scale disturbance and modification of the surface through mining or quarrying. Maps of superficial deposits may already include references to the types and origins of landforms that comprise them, such as moraines, eskers, lacustrine or lake sediments and so on. If the depositional landforms are sufficiently large in size, they will register on the topographic map as contours, depending on the map scale. The correlation between landforms of erosional and depositional origin is important for later analysis of ecological and cultural patterns. Depending on the scale of analysis, it may be useful to delineate the main groupings of types, such as kame-and-kettle, basket-of-eggs, estuarine structures or flood plain morphology, as these groupings may define later subdivisions of landscape character and ecological types. Erosive structures carved out of the solid geology will display a number of forms, partly dependent on the characteristics of the parent rock. There will also be numerous places where the topographic map correlates with the map of geological structures when overlaid, because the weaknesses provided by jointing, faults or discontinuities are exploited by the erosive agent and show up as variations in topography...
eBook - ePub- Rattan Lal(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
...Each grouping was based on landforms resulting from a set of similar processes or a succession of processes. Similar regional groupings have been produced for the coterminous United States, [ 14, 15, 16 ] and for Alaska. [ 17 ] A genetic classification, or the mode of origin, has some overlap with descriptive systems because different manner of origin may produce different forms. Examples of genetic systems include the classification of volcanic rocks, [ 18 ] the classification of glacial landforms, [ 19, 20 ] and landslide types and processes. [ 21 ] LANDFORM DEVELOPMENT Landforms may be erosional or constructional in form, or a composite of both. Most landforms are the products of erosion, but many are formed by the deposition of sediments, by volcanic activity, or by movements from within the earth’s crust. Examples of depositional features include dunes, moraines, and spits. Examples of erosional features are water gaps, deflation basins, or arêtes. Lahars, lava plains, and volcanoes result from volcanic activity. The formation of many alluvial fans and subsequent episodes of erosion and sedimentation in the basin and range of the Western United States are triggered by tectonic uplift. LANDFORMS AND MAPPING Landforms are part of a continuum of near surface features, soils, and surficial sediments. Bloom [ 22 ] describes a landform in a continuum as a unit of systematic analysis. When mapping, distinctive landform populations need to be delineated. The patterns are identifiable in the field with aids such as topographic maps, aerial photography, geophysical surveys, land use maps, and other available information. Delineating landforms can sometimes simplify soil mapping. For example, in traversing a hillslope from its summit to its toe, one might recognize several differing soil map units...
eBook - ePubLandscape Grading
A Study Guide for the LARE
- Valerie E. Aymer(Author)
- 2020(Publication Date)
- Routledge(Publisher)
...Section Two Landforms 2.1 What are landforms? Landforms are the identifiable shapes that the earth naturally forms due to geological processes. As landscape architects, we mimic and manipulate these basic forms to create functional designs. The natural shapes we are most concerned with are plane surfaces, ridges, valleys, peaks and depressions. These are manifested differently throughout the world and are named by their vegetative and animal habitats. For example, a bog, a swamp, and a fen are different types of wetlands. The processes that form and sustain these different wetlands vary; and the types of bog, swamp, and fen vegetation varies, but the underlying shape they form is a depression, a low point in the topography. It is the underlying landform in all cases that we manipulate in landscape grading. These natural forms are most easily recognized on a larger scale (e.g. 100, 200, 500 scale). However, because these problems are at such a large scale, intricate grading is difficult. Identification of the landforms, knowing where to put the problem elements and calculating slope between contour lines becomes essential. 2.2 Watersheds Together, plane surfaces, ridges, valleys, peaks, and depressions form watersheds. A watershed is a natural drainage basin for a particular area. It carries surface runoff, water from rainfall events, from the highest regions of the watershed downhill until it collects in streams, rivers, ponds, and eventually the ocean. Watersheds can be divided into subdrainage basins where water flows to a particular stream or pond within a watershed or they can be linked together to form a larger watershed region. These larger watershed regions are not determined by state government boundaries, but often encompass several states or more than one country. Additional information about watershed processes can be found in the recommended reading...
eBook - ePub- Ro Charlton(Author)
- 2007(Publication Date)
- Routledge(Publisher)
...This is transported downslope, under the force of gravity, by processes of mass wasting. These include rapid mass movements, such as slides and debris flows, together with the much slower processes of creep and solifluction. Sediment is also produced by the erosive action of water, ice and wind. Processes of water erosion include rain splash, sheetwash, rilling and gullying. Soil erosion is a natural process, but it can be accelerated by human activity, with rates of soil removal exceeding rates of soil formation. Accelerated soil erosion is a major environmental problem worldwide. In order to assess rates of soil loss, various monitoring techniques are used. Models have also been developed to simulate erosion and soil loss. FURTHER READING Introductory texts Kirkby, M.J., 2005. Hillslope processes and landscape evolution. In: J. Holden (ed.), An Introduction to Physical Geography and the Environment. Pearson Education., Harlow, pp. 249–77. Covers weathering and mass movement in slightly more detail than is provided here. Summerfield, M.A., 1990. Global Geomorphology: An Introduction to the Study of Landforms. Longman, Harlow. Good, clearly written chapters on weathering and slope processes. More advanced texts Morgan, R., 2005. Soil Erosion and Conservation. Blackwell, Oxford. Comprehensive coverage of soil erosion processes, monitoring and modelling, and management. Poesen, J. et al., 2002. Gully erosion in dryland environments. In: L.J. Bull and M.J. Kirkby (eds), Dryland Rivers: Hydrology and Geomorphology of Semi-arid Channels. John Wiley & Sons., Chichester, pp. 229–62. Provides a summary of current understanding of gully erosion in dryland environments. Web sites The Soil Erosion Site, www.soilerosion.net. Here you will find a wide range of material relating to all aspects of soil erosion. With contributions from nearly 50 soil erosion experts, the site includes background information, links to photos and videos, and more specialist material....
eBook - ePubAustralian Soils and Landscapes
An Illustrated Compendium
- Neil N. McKenzie, David D. Jacquier, Ray R.F. Isbell, Katharine K. Brown(Authors)
- 2004(Publication Date)
- CSIRO PUBLISHING(Publisher)
...The Yellow and Grey Kandosols are saturated, have shallow depths to free water (0–2 m), and shed surplus water. The Red Kandosols have much greater depths to free water (4–11+ m) even though they are downslope. Source: Adapted from Coventry 1982, fig. 4 Erosional landscapes Erosion by water has shaped many Australian landscapes (Figure 3.13). Erosional processes can dominate for several reasons. They may be caused by the lowering of stream base-levels through downcutting or sea-level change. Alternatively, erosional processes may become widespread when a region is uplifted through tectonic activity. Erosional landscapes can also develop after areas are built up through various forms of deposition (e.g. lava flows, dust deposits) or when vegetation cover is reduced and the soil surface is exposed (e.g. due to climate change or exploitative forms of land use). The following case studies focus on the uplifted landscapes of eastern Australia. Case 5: Gullied lands of south-east Australia Environmental fluctuations throughout the Quaternary period provided long phases of landscape stability, in which soil formation proceeded, alternating with phases of instability, in which erosion and deposition also dominated. Such a model was originally developed to explain soil distribution in south-east Australia and it has been influential worldwide. 12 More recently, however, detailed studies of gully erosion and valley fills in the southern highlands of New South Wales have revealed that the picture is not so simple, and other factors are at work. 13 Figure 3.13: Erosional processes have shaped most Australian landscapes Photograph: Arthur Mostead Figure 3.14: One of the few remaining intact Chain of Ponds on the Southern Tablelands of New South Wales Photograph: Ian Prosser, CSIRO In south-east Australia, a major episode of gully erosion started in the late 1800s, also a period of rapid agricultural expansion...
eBook - ePubApplied Geomorphology
Binghamton Geomorphology Symposium 11
- Richard G. Craig, Jesse L. Craft, Richard G. Craig, Jesse L. Craft(Authors)
- 2020(Publication Date)
- Routledge(Publisher)
...Changes in the local baselevel can have more profound effects on the development and evolution of the topography of tributaries to the reservoir. ERODE has been used to increase our understanding of these effects. THE MODEL The program written in FORTRAN IV and referred to in its entirety as ERODE is the implementation and quantification of a conceptual model of slope development. This model is based upon observations and detailed surveys in an area of approximately 260 km 2 located about 32 km southwest of Moab, Utah, in southeastern Utah (Fig. 1). The study area is a high plateau into which canyons of more than 680 m have been carved. The resistant sandstone that forms the vertical cliffs of the area is intersected by a rectangular system of joints. During a period of 6 years, extensive observations were made of the study area. Detailed surveys of the topography were made to illustrate the subtle variations in the landform morphology. Evidence of erosional processes was found and documented. Changes in the topographic form over this period of time were recorded to establish relative influence of the processes on the landscape. Details of these observations are presented elsewhere (Vanderpool 1979). From this came the identification of the predominant erosional processes. Figure 1 Location of study area in Utah; study area is outlined in inset. Slope development is considered to be the response of the land surface to two groups of exopenic processes: downslope transportation and fluvial downcutting (Fig. 2). Although this model simulates a semi-arid terrain where wind would be expected to be a significant process, very little silt or sand size sediments is found unprotected by larger material (talus). As a result, wind is a quite minor process and was ignored in this model. There are two energy sources for the system defined in the simulation model...
